KR102611346B1 - Remote plasma based deposition of graded or multi-layered silicon carbide film - Google Patents

Abstract

Methods and apparatus are provided for depositing graded or multi-layered silicon carbide films using remote plasma. A graded silicon carbide film or a multilayer silicon carbide film can be formed under process conditions that provide one or more organosilicon precursors on a substrate in a reaction chamber. Radicals of the source gas in a substantially low energy state, such as radicals of hydrogen in the ground state, are provided into the reaction chamber from a remote plasma source. In addition, co-reactant gas flows towards the reaction chamber. In some implementations, radicals of the co-reactant gas are provided into the reaction chamber from a remote plasma source. The flow rate of the co-reactant gas increases over time to form a graded silicon carbide film or a multilayer silicon carbide film having a compositional gradient from the first surface to the second surface of the graded silicon carbide film, or It can change gradually.

Description

REMOTE PLASMA BASED DEPOSITION OF GRADED OR MULTI-LAYERED SILICON CARBIDE FILM}

Cross-reference to related applications

This application claims the benefit of priority U.S. Patent Application No. 15/283,159, filed September 30, 2016, entitled “REMOTE PLASMA BASED DEPOSITION OF GRADED OR MULTI-LAYERED SILICON CARBIDE FILM,” the entire contents of which are incorporated herein by reference in their entirety. It is incorporated herein by reference for all purposes.

This disclosure relates generally to the formation of silicon carbide films, and more specifically to the deposition of graded silicon carbide films or multilayer silicon carbide films using remote plasma.

Thin films of the silicon carbide (SiC) family have unique physical, chemical and mechanical properties and are used in a variety of applications, especially integrated circuit (IC) applications. Thin films of the SiC family include oxygen-doped silicon carbide, also known as silicon oxycarbide, nitrogen-doped silicon carbide, also known as silicon nittricarbide, and oxygen- and nitrogen-doped silicon, also known as silicon oxynitride. Contains carbide.

The present disclosure relates to a method of depositing graded silicon carbide films. The method includes providing a substrate to a reaction chamber; Flowing an organosilicon precursor onto a substrate; flowing a co-reactant gas toward the reaction chamber; providing a source gas to a plasma source remote from the reaction chamber; generating, from the source gas, one or more radicals of the source gas in a plasma source; and introducing one or more radicals of the source gas onto the substrate. All or substantially all of the one or more radicals of the source gas are in a substantially low energy state that reacts with the organosilicon precursor. The method includes changing the flow rate of a co-reactant gas over time to form a graded silicon carbide film, wherein the graded silicon carbide film is The method further includes changing the flow rate of the co-reactant gas having a compositional gradient from the first surface to a second surface opposite the first surface of the graded silicon carbide film.

In some implementations, flowing the co-reactant gas toward the reaction chamber includes flowing the co-reactant gas through a plasma source. The method includes generating, from a co-reactant gas, one or more radicals of the co-reactant gas in a plasma source; and introducing one or more radicals of the co-reactant gas onto the substrate. In some implementations, flowing the co-reactant gas toward the reaction chamber includes flowing the co-reactant gas in the same flow path as the organosilicon precursor. In some embodiments, the co-reactant gas is oxygen gas. In some implementations, the graded silicon carbide film is a graded oxygen-doped silicon carbide (SiCO) film. In some implementations, the compositional gradient of the graded silicon carbide film can have an increasing concentration of carbon from a first surface to a second surface of the graded silicon carbide film. The concentration of carbon at the first surface of the graded silicon carbide film can be less than about 20% and the concentration of carbon at the second surface of the graded silicon carbide film can be greater than about 20%. In some implementations, the graded silicon carbide film is formed without introducing a vacuum break. In some embodiments, the low energy state radicals of the source gas include ground state hydrogen atomic radicals.

The present disclosure also relates to apparatus for depositing graded silicon carbide films. The apparatus includes a reaction chamber, a plasma source remote from the reaction chamber, a substrate support for holding a substrate within the reaction chamber, and the following operations: providing a substrate to the reaction chamber; Flowing an organosilicon precursor onto a substrate; flowing a co-reactant gas through a plasma source toward a reaction chamber; providing a source gas to the plasma source; generating, from the source gas, one or more radicals of the source gas in a plasma source; introducing one or more radicals of the source gas onto the substrate, wherein all or substantially all of the one or more radicals of the source gas are in a substantially low energy state to react with the organosilicon precursor. introducing them; and varying the flow rate of the co-reactant gas over time to form a graded silicon carbide film, wherein the graded silicon carbide film flows from the first surface to the opposite side of the first surface of the graded silicon carbide film. and a controller configured to perform steps of varying the flow rate of the co-reactant gas having a compositional gradient to the second surface.

In some implementations, the controller performs the following operations: generating, from a co-reactant gas, one or more radicals of the co-reactant gas at a plasma source, and generating one or more radicals of the co-reactant gas on a substrate. It further consists of instructions for performing the steps of introducing them. In some embodiments, the co-reactant gas is oxygen gas. In some implementations, the graded silicon carbide film is a SiCO film. In some implementations, the compositional gradient of the graded silicon carbide film can have an increasing concentration of carbon from a first surface to a second surface of the silicon carbide film. The concentration of carbon at the first surface of the graded silicon carbide film can be less than about 20% and the concentration of carbon at the second surface of the graded silicon carbide film can be greater than about 20%.

The present disclosure also relates to a method of depositing multilayer silicon carbide films. The method includes providing a substrate to a reaction chamber; Flowing an organosilicon precursor onto a substrate; flowing a co-reactant gas toward the reaction chamber; providing a source gas to a plasma source remote from the reaction chamber; generating, from the source gas, one or more radicals of the source gas in a plasma source; and introducing one or more radicals of the source gas onto the substrate. All or substantially all of the one or more radicals of the source gas are in a substantially low energy state that reacts with the organosilicon precursor. The method further includes increasing the flow rate of the co-reactant gas over time to form a multilayer silicon carbide film, the multilayer silicon carbide film having a varying concentration across the thickness of the multilayer silicon carbide film. .

In some implementations, flowing the co-reactant gas toward the reaction chamber includes flowing the co-reactant gas through a plasma source. In some implementations, flowing the co-reactant gas toward the reaction chamber includes flowing the co-reactant gas in the same flow path as the organosilicon precursor. In some embodiments, the co-reactant gas is carbon dioxide (CO ₂ ), carbon monoxide (CO), water (H ₂ O), methanol (CH ₃ OH), oxygen (O ₂ ), ozone (O ₃ ), nitrogen. (N ₂ ), nitrous oxide (N ₂ O), ammonia (NH ₃ ), diazine (N ₂ H ₂ ), methane (CH ₄ ), ethane (C ₂ H ₆ ), acetylene (C ₂ H ₂ ), ethylene (C ₂ H ₄ ), diborane (B ₂ H ₆ ), or combinations thereof. In some implementations, each layer of the multilayer silicon carbide film has an increasing concentration of carbon from a first surface of the multilayer silicon carbide film to a second surface opposite the first surface. In some implementations, the multilayer silicon carbide film is formed without introducing a vacuum break. In some embodiments, radicals of the source gas in a substantially low energy state include ground state hydrogen atomic radicals.

The present disclosure relates to a method of depositing graded silicon carbide films. The method includes providing a substrate to a reaction chamber; Flowing an organosilicon precursor onto a substrate; flowing a co-reactant gas toward the reaction chamber; providing a source gas to a plasma source remote from the reaction chamber; generating, from the source gas, one or more radicals of the source gas in a plasma source; and introducing one or more radicals of the source gas onto the substrate. All or substantially all of the one or more radicals of the source gas are in a substantially low energy state that reacts with the organosilicon precursor. The method includes varying the flow rate of an organosilicon precursor over time to form a graded silicon carbide film, wherein the graded silicon carbide film flows from a first surface of the graded silicon carbide film. and varying the flow rate of the co-reactant gas having a compositional gradient to a second surface opposite the first surface.

In some implementations, changing the flow rate of the organosilicon precursor over time occurs without changing the flow rate of the co-reactant gas or source gas. In some implementations, flowing the co-reactant gas toward the reaction chamber includes flowing the co-reactant gas through a plasma source. In some implementations, flowing the co-reactant gas toward the reaction chamber includes flowing the co-reactant gas in the same flow path as the organosilicon precursor. In some implementations, the graded silicon carbide film is a SiCO film. In some implementations, the compositional gradient of the graded silicon carbide film can have an increasing concentration of carbon from a first surface to a second surface of the graded silicon carbide film. The concentration of carbon at the first surface of the graded silicon carbide film can be less than about 20% and the concentration of carbon at the second surface of the graded silicon carbide film can be greater than about 20%. In some implementations, the graded silicon carbide film is formed without introducing a vacuum break. In some embodiments, the low energy state radicals of the source gas include ground state hydrogen atomic radicals.

These and other embodiments are further described below with reference to the drawings.

1A illustrates a cross-section of an exemplary silicon carbide film deposited on a substrate.
1B illustrates silicon carbide vertical structures on the sidewalls of the gate electrode structure of a transistor.
1C illustrates silicon carbide vertical structures on the exposed sidewalls of the copper lines of an air gap type metallization layer.
1D illustrates silicon carbide pore sealants for porous dielectric materials.
Figure 2 illustrates examples of representative caged siloxane precursors.
Figure 3 illustrates a schematic diagram of a device with a remote plasma source.
Figure 4 illustrates a cross-section of an exemplary graded silicon carbide film deposited on a substrate.
Figure 5 shows a graph illustrating the flow rate of organosilicon precursor flow rate and co-reactant gas over time.
Figure 6 shows a graph illustrating compositional profiles of carbon concentration as a function of depth for graded and ungraded silicon carbide films.
7 illustrates a scanning transmission electron microscopy (STEM) image of an exemplary oxygen-doped silicon carbide (SiCO) film (graded or ungraded) deposited within a feature of a substrate.
FIG. 8A illustrates a line scan graph of the STEM image of FIG. 7 showing the composition profile of an ungraded SiCO film.
FIG. 8B illustrates a line scan graph of the STEM image of FIG. 7 showing the composition profile of a graded SiCO film.

In the following description, numerous specific details are mentioned to provide a thorough understanding of the concepts presented. The concepts presented may be practiced without some or all of these specific details. In other instances, well-known process operations have not been described in detail so as not to unnecessarily obscure the concepts described. Although some concepts will be described in conjunction with specific embodiments, it will be understood that these embodiments are not intended to be limiting.

In this disclosure, the terms “semiconductor wafer,” “wafer,” “substrate,” “wafer substrate,” and “partially fabricated integrated circuit (IC)” are used interchangeably. Those skilled in the art will understand that the term “partially fabricated IC” can refer to a silicon wafer during any of the many stages of IC fabrication on top of it. Wafers and substrates used in the semiconductor device industry typically have a diameter of 200 mm, or 300 mm, or 450 mm. The detailed description below assumes that the present disclosure is implemented on a wafer. However, the present disclosure is not so limited. A work piece may be made of various shapes, sizes and materials. In addition to semiconductor wafers, other work pieces that may take advantage of the present disclosure include various articles such as printed circuit boards and the like.

introduction

Fabrication of semiconductor devices typically involves depositing one or more thin films on a substrate in an integrated manufacturing process. In some aspects of the manufacturing process, classes of thin films, such as silicon carbide, silicon oxycarbide, silicon nitricharbide, and silicon oxynitride carbide, are formed using atomic layer deposition (ALD), chemical vapor deposition (CVD), or plasma-enhanced deposition (PECVD). Deposited using enhanced chemical vapor deposition, or any other suitable deposition method. As used herein, the term silicon carbide includes doped silicon carbides such as oxygen doped silicon carbide, nitrogen doped silicon carbide, and nitrogen and oxygen doped silicon carbide. Most doped silicon carbides have up to about 50 atomic percent dopant atoms, whether these atoms are oxygen, nitrogen, or atoms of another element. The doping level provides targeted film properties.

One exemplary class of thin films that can be deposited includes silicon oxycarbide. As used herein, silicon oxycarbide may refer to a chemical compound containing silicon, oxygen, and carbon. Silicon oxycarbide may be used interchangeably with oxygen-doped silicon carbide, which may include SiCO or SiOC films.

Precursor molecules for depositing silicon carbides include silicon-containing molecules with silicon-hydrogen (Si-H) and/or silicon-silicon (Si-Si) bonds, and silicon-carbon (Si-C) bonds. can do. Precursor molecules for depositing silicon oxycarbides include silicon-hydrogen (Si-H) bonds and/or silicon-silicon (Si-Si) bonds, and silicon-oxygen (Si-O) bonds and/or silicon -Contains silicon-containing molecules with carbon (Si-C) bonds. Precursor molecules for depositing silicon nitricarbides include silicon-hydrogen (Si-H) bonds and/or silicon-silicon (Si-Si) bonds, and silicon-nitrogen (Si-N) bonds and/or Includes silicon-containing molecules with silicon-carbon (Si-C) bonds. Precursor molecules for depositing silicon oxynitrite carbides include silicon-hydrogen (Si-H) bonds and/or silicon-silicon (Si-Si) bonds, and silicon-nitrogen (Si-N) bonds, silicon -Includes silicon-containing molecules having oxygen (Si-O) bonds, and/or silicon-carbon (Si-C) bonds. Current PECVD processes may use in situ plasma processing, where the plasma is provided directly adjacent to the substrate.

Depositing high quality silicon carbide thin films provides excellent step coverage, low dielectric constants, high breakdown voltages, low leakage currents, high porosity, and/or exposed metal surfaces without oxidizing them. It has been found that there may be specific challenges, such as providing films with coverage on metal surfaces.

Without wishing to be limited by any particular theory, the plasma conditions in conventional PECVD processes fragment silicon-containing precursor molecules in a way that creates undesirable effects. For example, PECVD may break Si-O and/or Si-C bonds of precursor molecules to generate highly reactive radicals or other fragment types with high sticking coefficients. there is. The resulting doped silicon carbide film fragments may contain silicon, carbon, and/or oxygen atoms with “dangling” bonds, where “dangling” refers to silicon, carbon, and/or oxygen atoms having “dangling” bonds. This means that the atom has reactive, unpaired valence electrons. High adhesion coefficients precursor molecules and their fragments can create silicon carbide films with poor step coverage because the reactive precursor fragments may adhere disproportionately to the upper regions of the sidewalls and other structures in the recessed features. can be deposited.

Dangling bonds can create silanol groups (Si-OH) within the deposited silicon oxycarbide or silicon oxynitride film. As a result, the film may have detrimentally high dielectric constants. Film quality may also deteriorate because direct plasma conditions tend to extract carbon from the deposited film.

Moreover, dangling bonds can create increased silicon-hydrogen bonding (Si-H) in deposited silicon carbide films. The Si-C of the cleaved bonds can be replaced by Si-H in direct plasma deposition conditions. The presence of Si-H bonds in silicon carbide films can result in films with poor electrical properties. For example, the presence of Si-H bonds can create breakdown voltages and increase leakage currents because Si-H bonds provide a leakage path for electrons.

Additionally, dangling bonds can cause uncontrolled chemical or morphological structure in silicon carbide films. In some cases, these structures are dense filaments with low or no porosity, such that the filaments have an unacceptably high dielectric constant. The lack of porosity may be a result of direct plasma conditions that cleave Si-C and/or Si-O bonds in cyclic siloxanes that would otherwise provide porosity in ultralow-k (ULK) dielectric materials.

The direct plasma conditions sometimes employed in PECVD can cause directivity in deposition because the energy to split the precursor molecules can be low frequency, creating many ion bombardments at the surface. Directional deposition can also result in the deposition of silicon carbide films with poor step coverage. A direct plasma is a plasma in which the plasma (with an appropriate concentration of electrons and positive ions) remains adjacent to the substrate surface during deposition, sometimes separated from the substrate surface only by a plasma sheath.

Conventional PECVD processes are sometimes inadequate for depositing silicon carbide films on exposed copper or other metal surfaces because these processes can oxidize the metal. The PECVD process may use oxidizing agents such as oxygen (O ₂ ), ozone (O ₃ ), carbon dioxide (CO ₂ ), or other oxidizing species to form the silicon oxycarbide film.

Environment of the substrate surface during deposition

1A illustrates a cross-section of an exemplary silicon carbide film deposited on a substrate. Silicon carbide film 101 may be formed under process conditions that create a relatively mild environment adjacent to substrate 100. Substrate 100 may be any wafer, semiconductor wafer, partially fabricated IC, printed circuit board, display screen, or other suitable work piece. The process for depositing the silicon carbide film 101 includes, depending on the type of doped structure to be created, along with other bonds such as Si-C bonds, Si-O bonds, and/or Si-N bonds. It may involve one or more silicon-containing precursors having one or more Si-H bonds and/or one or more Si-Si bonds.

Specific applications employing oxygen-doped silicon carbide films are shown in FIGS. 1B-1D. In some embodiments, the silicon-containing precursors may include silicon-oxygen containing precursors, silicon-nitrogen containing precursors, and/or silicon-carbon containing precursors. Silicon-oxygen containing precursors can contain one or more Si-O bonds, silicon-nitrogen containing precursors can contain one or more Si-N bonds, and silicon-carbon containing precursors can contain one or more Si-C bonds. It can be included. In some embodiments, for example, silicon-containing precursors may include reactant A with Si-O bonds and Si-C bonds. In some embodiments, silicon-containing precursors may include reactant B, which has Si-O bonds, and reactant C, which has Si-C bonds. It will be understood that any number of suitable reactants may be employed within the scope of the present disclosure. Chemical structures of exemplary silicon-containing precursors are discussed in more detail below.

Silicon-containing precursors include one or more Si-H bonds and/or one or more Si-Si bonds. During the deposition process, Si-H bonds and/or Si-Si bonds are cleaved and serve as reactive sites to form bonds between the silicon-containing precursors of the deposited silicon carbide film 101. . Cleaved bonds can also serve as sites for cross-linking during thermal processing performed during or after deposition. Bonding and cross-linking at the reactive sites can collectively form a primary backbone or matrix in the resulting silicon carbide film 101.

In some embodiments, process conditions can substantially protect the Si-C bonds, and Si-O and Si-N bonds, if present, of the layer of silicon carbide film 101 as deposited. Accordingly, the reaction conditions adjacent to the substrate 100 provide for selective cleavage of Si-H bonds and/or Si-Si bonds, for example, extracting hydrogen from the cleaved Si-H bonds. They do not provide for extraction of oxygen from Si-O bonds, nitrogen from Si-N bonds, or carbon from Si-C bonds. However, as discussed below, the introduction of a co-reactant such as oxygen can also extract carbon from Si-C bonds. Generally, the described reaction conditions exist on the exposed side of the substrate 100 (the side on which the silicon carbide film 101 is deposited). These conditions may also exist at a distance above the substrate 100, for example, from about 0.5 μm to about 150 mm above the substrate 100. In fact, activation of the precursor may occur in the gas phase at a considerable distance above the substrate 100. Typically, the relevant reaction conditions will be uniform or substantially uniform over the entire exposed surface of substrate 100, although specific applications may allow for some variation.

In addition to silicon-containing precursors, the environment adjacent to the work piece (e.g., substrate 100) may include one or more radical species, preferably in a substantially low energy state. Examples of such species include hydrogen atomic radicals. In some embodiments, all, or substantially all, or a significant fraction of the hydrogen atom radicals are in the ground state, e.g., at least about 90% or 95% of the hydrogen atom radicals adjacent to the work piece are in the ground state. is in a state In certain embodiments, the source gas is provided as a carrier gas, such as helium. As an example, hydrogen gas may be provided on a helium carrier at a hydrogen concentration of about 1 to 10%. The pressure, fraction of carrier gas such as helium, and other process conditions are selected such that the hydrogen atoms encounter the substrate 100 because the radicals in the low energy state do not recombine.

As described elsewhere, hydrogen gas may be supplied into a remote plasma source to generate atomic hydrogen radicals or hydrogen radicals. Once generated, hydrogen atomic radicals may be in an excited energy state. For example, hydrogen in its excited energy state can have an energy of at least 10.2 eV (the first excited state). Excited hydrogen atomic radicals may cause unselective decomposition of the silicon-containing precursor. For example, hydrogen atom radicals in an excited state can easily cleave Si-H, Si-Si, Si-N, Si-O, and Si-C bonds, which affects the composition of the silicon carbide film 101. Or the physical properties or electrical properties may be changed. In some embodiments, when the excited hydrogen atom radicals lose energy or relax, the excited hydrogen atom radicals may become substantially low-energy state hydrogen atom radicals or ground state hydrogen atom radicals. Substantially low energy state or ground state hydrogen atom radicals can selectively cleave Si-H bonds and Si-Si bonds while generally preserving Si-O bonds, Si-N bonds, and Si-C bonds. . In some implementations, process conditions may be provided such that excited hydrogen atomic radicals substantially lose energy or relax to form low energy state or ground state hydrogen atomic radicals. For example, the remote plasma source or associated components may be designed such that the residence time of hydrogen atom radicals diffusing from the remote plasma source to the substrate 100 is longer than the energetic relaxation time of the excited hydrogen atom radicals. The relaxation time of energy for excited hydrogen atom radicals may be approximately equal to or less than about 1x10 ^-3 seconds.

A state in which a significant fraction of hydrogen atomic radicals is in the ground state can be achieved by various techniques. Some devices, such as those described below, are designed to achieve this condition. Device features and process control features can be tested and tuned to create a benign state in which a significant fraction of hydrogen atomic radicals are in the ground state. For example, the device may be downstream of a plasma source; That is, it may be operated and tested for charged particles near the substrate 100. The process and apparatus may be tuned until substantially no charged paper is present in the vicinity of the substrate 100. Additionally, device features and process features may be tuned to a configuration that begins to produce silicon carbide film 101 from a standard precursor such as trimethylsilane. Relatively mild conditions are chosen to support this film deposition.

Other examples of radical species are oxygen-containing species such as elemental oxygen radicals (atomic or diatomic), nitrogen-containing species such as elemental nitrogen radicals (atomic or diatomic), and nitrogen is selected into the film. Possibly incorporating N-H containing radicals such as ammonia radicals. Examples of N-H containing radicals include, but are not limited to, the radicals of methylamine, dimethylamine, and aniline. The radical species described above may be generated from a source gas containing hydrogen, nitrogen, N-H containing species, or mixtures thereof. In some embodiments, substantially all or a significant fraction of the atoms of the deposited film are provided by precursor molecules. In these cases, the low energy radicals used to drive the deposition reaction may be exclusively hydrogen or other species that do not substantially contribute to most of the deposited layer. In some embodiments, radical species may be generated by a remote plasma source, as discussed in more detail below. In some embodiments, higher energy state radicals or even ions may potentially exist near the wafer plane.

In some embodiments, the process conditions are sufficient to cleave Si-H bonds and/or Si-Si bonds while substantially preserving Si-O, Si-N, and Si-C bonds. Radical species are employed. These process conditions may not have significant amounts of ions, electrons or radical species in high energy states such as states above the ground state. In some embodiments, the concentration of ions in the area adjacent to the membrane is no greater than about 10 ⁷ /cm3. The presence of significant amounts of ions or high-energy radicals may tend to cleave Si-O bonds, Si-N bonds, and Si-C bonds, leading to undesirable electrical properties (e.g., high dielectric constants). constants and/or low breakdown voltages) and poor conformality. It is believed that an excessively reactive environment produces reactive precursor fragments with high adhesion coefficients (indicative of the tendency to chemically or physically adhere to the work piece sidewalls) and results in poor conformality.

In the environment adjacent to the substrate 100, silicon-containing precursors are typically transferred with other species, particularly carrier gases. In some implementations, silicon-containing precursors are present together with other species, including radical species and other reactive species and/or carrier gases. In some embodiments, silicon-containing precursors may be introduced as a mixture. Upstream from the deposition reaction surface, silicon-containing precursors can be mixed with an inert carrier gas. Exemplary inert carrier gases include, but are not limited to, nitrogen (N ₂ ), argon (Ar), and helium (He). In addition, the silicon-containing precursors may be introduced as a mixture having a major species and a minor species, with the minor species present in relatively low concentrations within the silicon carbide film 101 or It has structural features (e.g., ring structure, cage structure, unsaturated bonds, etc.). The plurality of precursors may be present in equimolar or relatively similar proportions as appropriate to form the primary backbone or matrix in the resulting silicon carbide film 101. In other embodiments, the relative amounts of different precursors are significantly distorted from equimolar.

In some embodiments, one or more silicon-containing precursors are used to form most of the deposited silicon carbide film ( 101) is essentially provided. In some embodiments, only radical species and one or more silicon-containing precursors contribute to the composition of the deposited silicon carbide film 101. In other embodiments, the deposition reaction includes one or more silicon-containing precursors and a co-reactant in addition to the radical species. Examples of these co-reactants are carbon dioxide (CO ₂ ), carbon monoxide (CO), water (H ₂ O), methanol (CH ₃ OH), oxygen (O ₂ ), ozone (O ₃ ), and nitrogen (N ₂ ). , nitrous oxide (N ₂ O), ammonia (NH ₃ ), diazine (N ₂ H ₂ ), methane (CH ₄ ), ethane (C ₂ H ₆ ), acetylene (C ₂ H ₂ ), ethylene (C- ₂ H ₄ ), diborane (B ₂ H ₆ ), and combinations thereof. These materials may be used as nitriding agents, oxidizing agents, reducing agents, etc. In some cases, they can be used to tune the amount of carbon in the deposited film by removing a fraction of the carbon provided with the silicon-containing precursor. In some implementations employing a non-hydrogen co-reactant, the co-reactant is sent via the same flow path as the silicon-containing precursor, for example, a path comprising a showerhead; Typically, it is introduced into the reaction chamber without direct exposure to the plasma. In some embodiments, oxygen and/or carbon dioxide is introduced with the precursor to change the composition of the silicon carbide film 101 by removing carbon from the film or precursor during deposition. In some embodiments employing a non-hydrogen co-reactant, the co-reactant is introduced into the reaction chamber via the same flow path as the hydrogen such that the co-reactant is at least partially converted to radicals and/or ions. do. In these implementations, both hydrogen radicals and co-reactant radicals react with the silicon-containing precursor(s) to produce the deposited silicon carbide film 101.

In certain embodiments, co-reactants are used and when the co-reactants are introduced into the chamber with a species to be converted to radicals (e.g., hydrogen), the co-reactants are converted to radicals (e.g., hydrogen). ) and a source of optional carrier gas(s), such as helium, may be provided to the reaction chamber in relatively small amounts compared to other gases in the reaction chamber. For example, the co-reactant may be present in the process gases at less than about 0.05% by mass, or less than about 0.01% by mass, or less than about 0.001% by mass. For example, the reactant mixture (entering the plasma source) may contain about 10 to 20 liters per minute (L/m) of He, about 200 to 500 standard cubic centimeters per minute (sccm) of H ₂ , and about 1 to 10 liters per minute (sccm) of H 2 . It could be sccm oxygen. When the co-reactants are introduced into the reaction chamber with the silicon-containing precursor (e.g., via a showerhead), the co-reactants are present at higher concentrations, e.g., about 2% or less or about 0.1% or less. It may exist as When the co-reactant is a relatively weak reactant (e.g., a weak oxidizing agent such as carbon dioxide), it may be present at much higher concentrations, such as up to about 10% or up to about 4%.

The temperature of the environment adjacent to the substrate 100 can be any suitable temperature that facilitates the deposition reaction, but is sometimes limited by the application of the device comprising the silicon carbide film 101. In some embodiments, the temperature of the environment adjacent to the substrate 100 may be controlled primarily by the temperature of the pedestal on which the substrate 100 is supported during deposition of the silicon carbide film 101. In some embodiments, the operating temperature may be from about 50°C to about 500°C. For example, operating temperatures can range from about 250°C to about 400°C for many IC applications. In some embodiments, increasing temperature can cause increased cross-linking on the substrate surface.

The pressure of the environment adjacent to the substrate 100 may be a pressure suitable to generate any reactive radicals within the reaction chamber. In some embodiments, the pressure may be about 35 Torr or less. For example, the pressure may be about 10 Torr to about 20 Torr, such as in embodiments implementing microwave generated plasma. In other examples, the pressure may be less than about 5 Torr, or between about 0.2 Torr and about 5 Torr, such as in embodiments implementing radio-frequency (RF) generated plasma.

1B-1D illustrate cross-sectional views of structures containing silicon carbide films in various applications. 1B illustrates silicon carbide vertical structures on the sidewalls of the gate electrode structure of a transistor. 1C illustrates silicon carbide vertical structures on the exposed sidewalls of copper lines in an air gap type metallization layer. Figure 1D illustrates a silicon carbide pore seal for porous dielectric materials. Each of these applications is discussed in more detail below.

Chemical structures of precursors

As discussed, precursors employed to form silicon carbide films may include silicon-containing precursors with at least some silicon-containing precursors having at least one Si-H bond and/or at least one Si-Si bond. You can. In certain embodiments, the silicon-containing precursor has at most one hydrogen atom per silicon atom. Thus, for example, a precursor having one silicon atom will have at most one hydrogen atom bonded to the silicon atom; A precursor having two silicon atoms has one hydrogen atom bonded to one silicon atom and optionally another hydrogen atom bonded to a second silicon atom; A precursor with three silicon atoms has at least one hydrogen atom bonded to one silicon atom and optionally one or two more hydrogen atoms bonded to one or two or more remaining silicon atoms, and so on. Additionally, the silicon-containing precursors may include at least one Si-O bond, at least one Si-N bond, and/or at least one Si-C bond. Any number of suitable precursors can be used to form silicon carbide films, but at least some of the precursors have at least one Si-H bond or Si-Si bond, and optionally at least one Si-O bond, Si- It will include silicon-containing precursors having N bonds, and/or Si-C bonds. In various embodiments, the silicon-containing precursor(s) do not contain OC or NC linkages; For example, the precursor(s) does not include an alkoxy (-OR), where R is a hydrocarbon group, or an organic group such as an amine (-NR ₁ R ₂ ) group, and R ₁ and R ₂ is independently a hydrogen group or an organic group.

In certain embodiments, at least some of the carbon provided to the silicon carbide film is provided by one or more hydrocarbon moieties on the silicon-containing precursor. These moieties may be moieties from alkyl groups, alkene groups, alkyne groups, aryl groups, etc. In certain embodiments, the hydrocarbon group has a single carbon atom to minimize steric hindrance of Si-H and/or Si-Si bond cleavage reactions during deposition. However, precursors are not limited to single-carbon groups, and larger numbers of carbon atoms may be used, such as 2, 3, 4, 5, or 6 carbon atoms. In certain embodiments, the hydrocarbon group is linear. In certain embodiments, the hydrocarbon group is cyclic.

In some embodiments, silicon-containing precursors are divided into chemical classes. It will be understood that other chemical classes of silicon-containing precursors may be employed and that the silicon-containing precursors are not limited to the chemical classes discussed below.

In some embodiments, the silicon-containing precursor can be a siloxane. In some embodiments, the siloxane may be cyclic. Cyclic siloxanes include cyclotetrasiloxanes, such as 2,4,6,8-tetramethylcyclotetrasiloxane (TMCTS: 2,4,6,8-tetramethylcyclotetrasiloxane) and octamethylcyclotetrasiloxane (OMCTS: octamethylcyclotetrasiloxane). ), and heptamethylcyclotetrasiloxane (HMCTS: heptamethylcyclotetrasiloxane). Other cyclic siloxanes may also include, but are not limited to, cyclotrisiloxanes and cyclopentasiloxanes. Embodiments using cyclic siloxanes are ring structures that can introduce porosity into an oxygen-doped silicon carbide film, with the size of the pores corresponding to the radius of the ring. For example, a cyclotetrasiloxane ring may have a radius of about 6.7 Å.

In some embodiments, the siloxane may have a three-dimensional or caged structure. Figure 2 illustrates examples of representative caged siloxane precursors. Caged siloxanes have silicon atoms bridged to each other through oxygen atoms to form a polyhedron or arbitrary 3-D structure. One example of a caged siloxane precursor molecule is silsesquioxane. Caged siloxane structures are described in more detail in commonly owned U.S. Patent No. 6,576,345 to Cleemput et al., the entire contents of which are incorporated herein by reference for all purposes. Like cyclic siloxanes, caged siloxanes can introduce porosity into oxygen-doped silicon carbide films. In some embodiments, the porosity size is mesoporous.

In some embodiments, the siloxane may be linear. Examples of suitable linear siloxanes include, but are not limited to, disiloxanes such as pentamethyldisiloxane (PMDSO) and tetramethyldisiloxane (TMDSO), and trisiloxanes such as hexamethyltrisiloxane, heptamethyldisiloxane, Contains methyltrisiloxane.

In some embodiments, the silicon-containing precursor may be an alkyl silane or other hydrocarbon-substituted silane. Alkyl silanes contain a central silicon atom with one or more hydrogen atoms bonded to the central silicon atom as well as one or more alkyl groups bonded to the central silicon atom. In certain embodiments, any one or more alkyl groups contain 1 to 5 carbon atoms. Hydrocarbon groups may be saturated or unsaturated (e.g., alkene (e.g., vinyl) groups, alkyne groups, and aromatics). Examples include, but are not limited to, trimethylsilane (3MS), triethylsilane, pentamethyl disilamethane ((CH ₃ ) ₂ Si-CH ₂ -Si(CH ₃ ) ₃ ) , and dimethylsilane (2MS: dimethylsilane).

In some embodiments, the silicon-containing precursor can be an alkoxy siloxane. Alkoxy siloxanes contain a central silicon atom with one or more alkoxy groups bonded to the central silicon atom and one or more hydrogen atoms bonded to the central silicon atom. Examples include, but are not limited to, trimethoxysilane (TMOS), dimethoxysilane (DMOS), methoxysilane (MOS), methyldimethoxysilane (MDMOS), diethyoxymethylsilane (DEMS), dimethylethoxysilane (DMES), and dimethylmethoxysilane (DMMOS).

Additionally, disilanes, trisilanes, or other higher silanes may be used in place of monosilanes. One example of such a disilane from the alkyl silane class is hexamethyldisilane (HMDS). Another example of a disilane from the alkyl silane class may include pentamethyldisilane (PMDS). Other types of alkyl silanes can include alkylcarbosilane, which can have a branched polymer structure with alkyl groups bonded to silicon atoms as well as carbon bonded to silicon atoms. Examples include dimethyl trimethylsilyl methane (DTMSM) and bis-dimethylsilyl ethane (BDMSE). In some embodiments, one of the silicon atoms may have a carbon-containing group or a hydrocarbon-containing group attached to the silicon atom, and one of the silicon atoms may have a hydrogen atom attached to the silicon atom.

When depositing silicon carbide, multiple silicon-containing precursors may be present in the process gas. For example, siloxanes and alkyl silanes may be used together, or siloxanes and alkoxy siloxanes may be used together. Relative proportions of individual precursors may be selected based on the chemical structures of the selected precursors and the application of the resulting silicon carbide film. For example, the amount of siloxane can be greater than the amount of silane by mole percentage to create a porous membrane, as discussed in more detail below.

For depositing oxygen-doped silicon carbide films, examples of suitable precursors include cyclic siloxanes such as cyclotetrasiloxanes, such as heptamethylcyclotetrasiloxane (HMCTS) and tetramethylcyclotetrasiloxane. Other cyclic siloxanes may also include, but are not limited to, cyclotrisiloxanes and cyclopentasiloxanes. For depositing oxygen-doped silicon carbide films, other examples of suitable precursors include, but are not limited to, linear siloxanes such as pentamethyldisiloxane (PMDSO), tetramethyldisiloxane (TMDSO), hexamethyltrisiloxane, and heptamethyl Contains trisiloxane.

As explained, silicon-containing precursors are selected to provide highly conformal silicon carbide films. It is believed that silicon-containing precursors with low adhesion coefficients can produce highly conformal films. “Attachment coefficient” is used to describe the ratio of the number of adsorbed species (e.g. fragments or molecules) that adsorb/attach to a surface compared to the total number of species impinging on the surface during the same period of time. It is an established term. The symbol S _c is sometimes used to refer to the attachment coefficient. The value of S _c is between 0 (meaning no species is attached) and 1 (meaning all conflicting species are attached). Various factors affect the adhesion coefficient, including the type of impinging species, surface temperature, surface coverage, structural details of the surface, and the kinetic energy of the impinging species. Certain species are inherently more "sticky" than others, making them more likely to adhere to a surface whenever they hit it. These stickier species (all other factors being equal) have higher adhesion coefficients and are better at adsorbing near the entrance of the recessed feature compared to less sticky species which have lower adhesion coefficients. In some cases, the attachment coefficient of the precursors (at relevant deposition conditions) may be less than or equal to about 0.05, such as less than or equal to about 0.001.

Graded Silicon Carbide Membrane

Technology nodes continue to shrink in the IC fabrication industry. With each technology node, device geometries shrink and the pitch becomes smaller. High aspect ratio gaps in these technology nodes may need to be filled with insulating material, which has a low dielectric constant (low-k). Semiconductor integration operations may involve filling high aspect ratio gaps using low-k dielectric materials. This corresponds to STI (shallow trench isolation), inter-metal dielectric layers, passivation layers, etc.

For example, going from a 45-nm technology node to a 14-nm technology node, device features shrink laterally, bringing the conductive materials closer together. As the conductive materials become closer together, unwanted conductive coupling may occur, which can cause parasitic capacitance, delay in signal propagation, and signal crosstalk due to capacitive effects. However, as technology nodes become smaller, low-k materials such as interlayer dielectric (ILD) of conductive interconnects can reduce parasitic capacitance, signal delay, and signal crosstalk. Some applications require low-k materials, such as sidewall spacer materials, including fin field effect transistor (finFET) structures and dynamic random-access memory (DRAM) bit structures.

Silicon nitride (Si ₃ N ₄ ) is often used as an insulating material in many IC applications because of its step coverage, thermal stability, etch-ability and etch resistance, and high breakdown voltages. However, the dielectric constant of silicon nitride, around 7 to 8, may become very high as technology nodes become smaller.

Silicon oxide (SiO ₂ ) has a lower dielectric constant of about 4.0 and can provide significant reduction in capacitance as an interlayer dielectric in conductive interconnects. However, silicon oxide may not have sufficient resistance or selectivity to the etch operations of the device integration flow.

Silicon carbide materials, including doped silicon carbide materials, provide not only low dielectric constant, but also step coverage, thermal stability, wet etch resistance, dry etch selectivity to oxide/nitride and high breakdown voltages. It may also serve as insulating materials in IC applications. Incorporation of oxygen atoms and/or nitrogen atoms may tune the properties of silicon carbide materials. In some embodiments, oxygen-doped silicon carbide films can serve as insulating materials in IC applications providing low dielectric constant, wet etch resistance to withstand device integration operations, and dry etch selectivity to oxides/nitrides. You can.

However, a single layer or film of oxygen-doped silicon carbide may not possess all of the desired properties, including possessing both a low dielectric constant and high etch resistance. In some embodiments, a multilayer stack may be provided, where each layer has different properties, and the multilayer stack serves as an insulating material in IC applications. For example, oxygen-doped silicon carbide films can have varying amounts of carbon content in a multilayer stack. The multilayer stack provides a top layer with wet etch resistance, dry etch selectivity to oxides/nitrides, and thermal stability to serve as a protective layer and a bottom layer with a low dielectric constant (e.g., k < 4.0). can do. The top layer provides wet etch resistance, high resistance to steam anneal, high resistance to ash and strip, high dry etch selectivity to oxides/nitrides, and high thermal stability. It may have a high elastic content in order to do so. The bottom layer may have a low carbon content to provide a low dielectric constant and excellent electrical properties, such as high breakdown voltage and low leakage current. Intermediate layers may be formed in between. Each layer may be formed by selecting a different precursor, which may be selected based on the relative concentrations of silicon, carbon, and oxygen. A layer with a high carbon content may employ a silicon-containing precursor with more Si-C bonds, and a layer with a low carbon content may employ a silicon-containing precursor with fewer Si-C bonds. Alternatively, each layer may be formed by varying the flow rate of the co-reactant gas relative to the flow rate of the silicon-containing precursor. Alternatively, each layer may be formed by varying the flow rate of the silicon-containing precursor. Accordingly, layer composition tuning can be achieved by appropriate precursor selection or co-reactant ratio selection to precursor gas flow rate.

Instead of a plurality of separate layers, the silicon carbide film can be graded from a first surface to a second surface opposite the first surface. In some embodiments, the first surface and the second surface may represent a bottom surface and a top surface, respectively. In some embodiments, the first surface and the second surface may represent a top surface and a bottom surface, respectively. In some embodiments, if the silicon carbide film is a sidewall spacer, the first surface may face the conductive interconnects and the second surface may be exposed to subsequent device integration operations. The graded silicon carbide film can have a compositional gradient from the first surface to the second surface. Compositional gradients can be provided across the thickness of the graded silicon carbide film. Accordingly, the properties of graded silicon carbide films can change gradually over the thickness of the film.

Multiple individual layers with varying compositions and properties may not be as robust as graded films and may have more interfacial problems in heterogeneous multilayer stacks. Multiple individual layers may require careful targeting of the thickness of the protective layer to prevent the possibility of failure. That is, if a silicon carbide layer with a high carbon concentration acts as a protective layer over a silicon carbide layer with a low carbon concentration, the thickness of the protective layer is carefully selected to withstand device integration operations; The silicon carbide layer may not hold up. However, graded silicon carbide films may provide more buffer zones for higher protection than multilayer silicon carbide films. Nonetheless, multiple individual layers of a multilayer silicon carbide film may not be equally compromised in terms of electrical properties (eg, low dielectric constant) since more multilayer silicon carbide films may have lower carbon concentrations.

Figure 4 illustrates a cross-section of an exemplary graded silicon carbide film deposited on a substrate. It should be understood that the various aspects of the graded silicon carbide film 401 not only apply to graded structures with compositional gradients, but that these aspects may also apply to multilayer structures.

Graded silicon carbide film 401 can be deposited on substrate 400 using the remote plasma-based deposition process described in this disclosure. Substrate 400 may be any wafer, semiconductor wafer, partially fabricated IC, printed circuit board, display screen, or other suitable work piece. The graded silicon carbide film 401 has a first surface 402 facing the substrate and a second surface 403 opposite the first surface 402. The graded silicon carbide film 401 of the present disclosure can be implemented in a variety of applications, including the structures shown in FIGS. 1B-1D, discussed in more detail below.

The graded silicon carbide film 401 includes silicon and carbon and, if applicable, oxygen and/or nitrogen. In some embodiments, the atomic concentration of silicon is between about 15% and 45% (or between about 25% and 40%), the atomic concentration of carbon is between about 5% and 50%, and the atomic concentration of oxygen is between about 0% and 45%, and the atomic concentration of nitrogen is about 0% to 45%. In one example, film 401 contains about 10 to 40 percent carbon and about 20 to 40 percent oxygen on an all-atomic basis. In all cases, film 401 contains some amount of hydrogen. It will be appreciated that the relative atomic concentrations may vary depending on the choice of precursor. Silicon atoms can form bonds with carbon atoms and oxygen atoms. In certain embodiments, the membrane density is about 2.0 to 2.7 g/cm3.

It will be appreciated that the overall composition of the graded silicon carbide film 401 can vary depending on the choice of precursor, flow of precursor, and flow of co-reactant gas. In some embodiments, the internal structure of the precursor is maintained within the deposited film. This structure is achieved by forming individual precursors through Si-H bonds and/or bonds at positions where Si-Si bonds exist within the precursor molecules and/or through additional condensation reactions on the growing surface if sufficient thermal energy is provided. While linking or cross-linking moieties, all or most Si-C bonds, and Si-O bonds and/or Si-N bonds, if present, may be preserved in the precursor.

The process conditions previously described herein can provide highly conformal film structures, regardless of whether the silicon carbide film is a graded or ungraded film. Relatively mild process conditions can minimize the degree of ion bombardment at the surface of the substrate, so the deposition is isotropic. Moreover, relatively mild process conditions can reduce the number of radicals with high attachment coefficients because they tend to adhere to the sidewalls of previously deposited layers or films. In certain embodiments, for depth-to-width aspect ratios of about 2:1 to 10:1, the graded silicon carbide film has a thickness of about 25% to 100%, more typically about 50% to 100%, and even more typically. It may be deposited with conformality of about 80% to 100%. Conformality may be calculated by comparing the average thickness of the film deposited on the bottom, sidewall, or top of the feature to the average thickness of the film deposited on the bottom, sidewall, or top of the feature. For example, conformality may be calculated by dividing the average thickness of the film deposited on the sidewall by the average thickness of the film deposited at the top of the feature and multiplying by 100 to obtain a percentage. For certain applications, a conformality of about 85% to 95% is sufficient. In some examples, when depositing graded silicon carbide on features having an aspect ratio of about 2:1 to about 4:1, the conformality is at least about 90%. Certain BEOL (back end of line) processes fall into this category. In some examples, when depositing graded silicon carbide on features having an aspect ratio of about 4:1 to about 6:1, the conformality is at least about 80%. Certain spacer deposition processes fall into this category. In some examples, when depositing graded silicon carbide on features having an aspect ratio of about 7:1 to about 10:1 (and even higher), the conformality is at least about 90%. Certain DRAM manufacturing processes fall into this category.

These process conditions can also provide a membrane structure with high breakdown voltage and low leakage current. By introducing a limited amount of oxygen or nitrogen into the silicon carbide family of materials, the leakage paths provided by Si-H bonds and/or Si-CH ₂ -Si bonds may be blocked by the oxygen or nitrogen. . The conduction mode may be different for Si-O and Si-N at low magnetic fields. This can provide improved electrical properties while maintaining a relatively low dielectric constant. In various embodiments, the membrane has a density of about 6.0 or less, or about 5.0 or less, or about 4.0 or less, and in some cases, about 3.5 or less, and in some cases, about 3.0 or less, and in still other embodiments, about 2.5 or less. It has an effective dielectric constant. For film structures with an effective dielectric constant of 3.5 or less, an appropriate flow rate of co-reactant gas and an appropriate silicon-containing precursor can be selected. The effective dielectric constant can be dependent on coupling and density. In certain embodiments, oxygen-doped silicon carbide films have a dielectric constant greater than 5.0, especially when the carbon content is relatively high. If leakage current is an important consideration, oxygen-doped silicon carbide films should be less than about 5.0. The smaller the dielectric constant, the worse the hermetic and barrier and thermal resistance properties.

In some implementations, the graded silicon carbide film includes oxygen doped silicon carbide, which may generally refer to SiOC or SiCO. As used herein, however, SiOC is not the same as SiCO because SiOC films do not have the same chemical structure or properties as SiCO films. The SiCO film may exhibit a chemical structure deposited by the remote plasma-based deposition process of the present disclosure. SiCO films contain few or no terminal CH ₃ bonds, and the carbon atoms are generally cross-linked and coordinated by the silicon atoms. The carbon atoms, or at least the top fraction of carbon atoms, are cross-linked and not coordinated by hydrogen or oxygen atoms. In addition, SiCO films have relatively low hydrogen content. In contrast, the SiOC film contains multiple terminal CH ₃ bonds, and the carbon atoms are coordinated by oxygen and hydrogen atoms. The carbon atoms, or at least the top fraction of carbon atoms, are not cross-linked. In addition, SiOC films have relatively high hydrogen content. SiOC films are generally not as thermally and chemically stable as SiCO films. It is understood that in some embodiments, the graded silicon carbide film of the present disclosure is a graded SiCO film.

Although many of the examples below refer to graded SiCO films, it is understood that the graded silicon carbide film of the present disclosure can also be applied to silicon oxynitride carbide (SiONC) films and silicon nitricarbide (SiNC) films. It will be. Silicon carbide films may therefore refer to SiC, SiCO, SiONC, and SiNC films. In some implementations, graded SiONC films or graded SiNC films can be deposited using different precursors and/or a different co-reactant gas than SiCO films. In some implementations, the co-reactant gas may include, for example, N ₂ , N ₂ O, NH ₃ , N ₂ H ₂ , or combinations thereof.

Graded silicon carbide films can be deposited using remote plasma-based deposition techniques described in this disclosure. Graded silicon carbide films can be deposited in situ with or without a vacuum break (eg, an air break). Vacuum breaks can introduce oxidation into semiconductor devices, which can lead to higher electrical resistance and reduced performance. Furthermore, vacuum breaks can reduce throughput. Graded silicon carbide films also reduce interfacial brittleness that can result from multiple deposition processes for multiple individual layers.

The process for depositing a graded silicon carbide film involves one or more bonds along with other bonds such as Si-C bonds, Si-O bonds, and/or Si-N bonds, depending on the type of doped structure to be created. It may involve one or more silicon-containing precursors having Si-H bonds and/or one or more Si-Si bonds. The one or more silicon-containing precursors may include any silicon-containing precursor as discussed above. In some implementations, the one or more silicon-containing precursors include an organosilicon precursor. The organosilicon precursor may flow into the reaction chamber and onto a substrate provided within the reaction chamber. When depositing a graded SiNC film, the organosilicon precursor comprises: (i) one or more Si-H bonds and/or Si-Si bonds, (ii) one or more Si-C bonds, and (iii) one or more Si-C bonds. May contain -N bonds. When depositing a graded SiCO film, the organosilicon precursor is comprised of: (i) one or more Si-H bonds and/or Si-Si bonds, (ii) one or more Si-C bonds, and (iii) one or more Si-Si bonds. May contain -O bonds. For example, the organosilicon precursor can be selected from the group consisting of: cyclic siloxanes, linear siloxanes, and alkoxy siloxanes.

In addition to one or more silicon-containing precursors, the process for depositing a graded silicon carbide film can preferably involve one or more radical species that are in a substantially low energy state (e.g., ground state). One or more radical species in a substantially low energy state may be provided as described above. A source gas, such as hydrogen gas, may be supplied into the remote plasma source. The remote plasma source may generate radicals of the source gas and may introduce radicals of the source gas onto the substrate. In some embodiments, the one or more radical species include one or more hydrogen atom radicals. Because hydrogen atomic radicals may transition from an excited state to a relaxed state, hydrogen atomic radicals may be introduced onto the substrate in a substantially low energy state. Hydrogen radicals in a substantially low energy state or ground state can selectively cleave Si-H bonds and Si-Si bonds, while generally preserving Si-O, Si-N, and Si-C bonds. In some embodiments, at least 90% of the radical species in the source gas are ground state hydrogen atomic radicals. A state in which a significant fraction of hydrogen atomic radicals is substantially in a low energy state or ground state can be achieved by a variety of techniques. Some devices, as described below, are designed to achieve this condition.

Additionally or alternatively, the one or more radical species may be an oxygen-containing species, such as elemental oxygen radicals (atomic or diatomic), a nitrogen-containing species, such as elemental nitrogen radicals (atomic or diatomic). , and N-H containing radicals such as ammonia radicals, with nitrogen optionally incorporated into the film.

Process conditions for depositing graded silicon carbide films may not have significant amounts of ions, electrons or radical species in high energy states such as states above the ground state. In some embodiments, the concentration of ions in the area adjacent to the membrane is no greater than about 10 ⁷ /cm3. Other process conditions, such as pressure and temperature, may be similarly applied to deposit graded silicon carbide films, as described above.

In certain embodiments, the source gas is provided as a carrier gas, such as helium. As an example, hydrogen gas may be provided on a helium carrier at a hydrogen concentration of about 1 to 10%. The pressure, fraction of carrier gas such as helium, and other process conditions are chosen such that the hydrogen atoms face the substrate because radicals in the lower energy state do not recombine.

The process for depositing a graded silicon carbide film may involve one or more silicon-containing precursors and a co-reactant other than one or more radical species in the source gas. Exemplary co-reactants include O ₂ , CO ₂ , CO, H ₂ O, CH ₃ OH, O ₃ , N ₂ , N ₂ O, NH ₃ , N ₂ H ₂ , CH ₄ , C ₂ H ₆ , C ₂ H ₂ , C ₂ H ₄ , B ₂ H ₆ , and combinations thereof. In some embodiments of depositing graded SiCO films, the co-reactants can include O ₂ , CO ₂ , CO, O ₃ , N ₂ O, and combinations thereof. In some embodiments of depositing graded SiNC films, the co-reactants can include N ₂ , NH ₃ , N ₂ H ₂ , and combinations thereof.

The co-reactant may flow toward the reaction chamber, and the flow path of the co-reactant may be with the silicon-containing precursor or with the source gas. In some embodiments employing a non-hydrogen co-reactant, the co-reactant is flowed via the same flow path as the silicon-containing precursor, e.g., a path comprising a showerhead, typically without direct exposure to the plasma. introduced into the reaction chamber. In some embodiments employing a non-hydrogen co-reactant, the co-reactant is introduced into the reaction chamber via the same flow path as the source gas (e.g., hydrogen), and the co-reactant is The material may flow through the plasma source toward the reaction chamber such that it is at least partially converted into radicals and/or ions. Accordingly, one or more radicals of the co-reactant can be generated within the remote plasma source and one or more radicals of the co-reactant can be introduced into the reaction chamber. When co-reactants are introduced into the reaction chamber, they may be present in relatively small amounts compared to some of the other gases provided within the reaction chamber. In some embodiments, the flow rate of the co-reactant gas can be less than about 10 sccm, while the flow rate of the carrier gas and the flow rate of the source gas are each less than or equal to about 10 L/m.

The flow rate of the co-reactant gas can vary over time in the formation of a multilayer silicon carbide film or graded silicon carbide film. In some embodiments, the flow rate of the co-reactant gas can be changed gradually over time to form a compositional gradient of the graded silicon carbide film. In some embodiments, the flow rate of the co-reactant gas can be varied synergistically or in discrete time intervals over time to form a multilayer silicon carbide film. In some embodiments, the co-reactant gas is oxygen gas. In some embodiments, the flow rate of the organosilicon precursor may be constant while the flow rate of the co-reactant gas is varied.

In some embodiments, the flow rate of the organosilicon precursor can be varied while the flow rate of the co-reactant gas is varied. In some embodiments, the flow rate of the organosilicon precursor can vary while the flow rate of the co-reactant gas is constant. Similar to changing the flow rate of a co-reactant gas over time, changing the flow rate of an organosilicon precursor over time can form a compositional gradient in a graded silicon carbide film. The flow rate of the organosilicon precursor may vary gradually over time or may vary synergistically or in discrete time intervals over time. By varying the flow rate of the organosilicon precursor over time, multiple Si-C bonds can be tuned to tune the carbon content in the first and second surfaces.

Moreover, organosilicon precursors can be selected to tune the carbon content in the graded silicon carbide film. Different organosilicon precursors with different carbon content can be utilized when depositing at different time intervals when depositing a graded silicon carbide film. For example, a first organosilicon precursor with more carbon bonds may be selected for deposition on a first surface and a second organosilicon precursor with fewer carbon bonds may be selected for deposition on a second surface. You can. Changes in the organosilicon precursor when depositing a graded silicon carbide film can result in more drastic changes in the compositional gradient of the graded silicon carbide film.

When the flow rate of the co-reactant gas changes over time, the flow rate of the co-reactant gas changes without a vacuum break. Varying the flow rate of co-reactant gases to form a compositional gradient of a graded silicon carbide membrane provides a membrane with a more graded continuum in composition and can be more robust than a membrane with multiple individual layers.

Accordingly, the compositional gradient of the graded silicon carbide film changes the organosilicon precursor, the flow rate of the organosilicon precursor over time, and the flow rate of the co-reactant gas over time. Can be tuned by one or more techniques, including changing .

Figure 5 shows a graph illustrating the flow rate of the organosilicon precursor and the flow rate of the co-reactant gas, which is oxygen, over time. As shown in Figure 5, the flow rate of the organosilicon precursor can remain constant over time during the deposition of the graded silicon carbide film. The graded silicon carbide film can be a graded SiCO film. Although not shown, the flow rate of the source gas, which is hydrogen, and the carrier gas, which is helium, can be kept constant over time during the deposition of the graded silicon carbide film. However, the flow rate of the co-reactant gas, which is oxygen, changes synergistically over time. In Figure 5, the flow rate of oxygen decreases over time. As an example, the flow rate of oxygen starts at 9.5 sccm for the first 50 Å of the deposited film, then drops to 7.5 sccm for the next 50 Å of the deposited film, then drops to 5.5 sccm for the next 50 Å of the deposited film, and then This can drop to 3.5 sccm for the next 50 Å of the formed membrane. Each deposition of 50 Å of the deposited film may take from about 100 seconds to about 500 seconds, such as about 375 seconds. The flow rate of the organosilicon precursor can be maintained at a constant flow rate of about 8.0 sccm. However, it is understood that the flow rate of the organosilicon precursor may vary depending on the precursor chemistry. Although the graph in Figure 5 shows the change in flow rate as a stepped profile, it is understood that the change in flow rate could be a different profile, such as a sloped or curved profile.

By adjusting the flow rate of the co-reactants over time, the composition of the graded silicon carbide film varies across the thickness of the graded silicon carbide film. The presence of oxygen gas or oxygen radicals tends to extract carbon from Si-C bonds. In other words, the presence of oxygen can convert carbide to oxide. Carbon may be removed from the organosilicon precursor on the substrate and, in some instances, replaced with oxygen. Therefore, increasing the concentration of oxygen in the reaction mixture can effectively tune the carbon content of films such as graded SiCO films.

Alternatively, the presence of nitrogen gas or nitrogen radicals tends to extract carbon from Si-C bonds. Therefore, increasing the concentration of nitrogen in the reaction mixture can also effectively tune the carbon content of graded silicon carbide films, such as graded SiNC films.

In some embodiments, the compositional gradient of the graded silicon carbide film has the concentration of carbon rising from a first surface of the silicon carbide film to a second surface or vice versa. The first surface has a lower concentration of carbon, and the atomic concentration of carbon may be less than about 20%, less than about 15%, or less than about 10%. The second surface has a higher concentration of carbon, and the atomic concentration of carbon may be greater than about 20%, greater than about 30%, or greater than 35%. In some embodiments, the carbon concentration may range anywhere between about 1% and about 50% across the compositional gradient, or anywhere between about 5% and about 45% across the compositional gradient. In some implementations of the SiCO film, the first surface can have a carbon concentration approaching the chemistry for SiO ₂ and the second surface can have a carbon concentration approaching the chemistry for SiC. With decreasing concentration of oxygen in the reaction mixture over time, the film at the second surface can have more Si-C bonds and the film at the first surface can have fewer Si-C bonds. It is understood that the carbon concentration gradient can be reversed depending on the application.

As an example, the compositional gradient of a graded SiCO film has an increasing concentration of carbon from the bottom surface to the top surface, or vice versa. As used herein, the bottom surface of a graded SiCO film can refer to the surface deposited on the substrate or features of the substrate, and the top surface of the graded SiCO film is exposed to subsequent device integration operations. It can refer to the surface. In some embodiments, the atomic concentration of carbon at the bottom surface is less than about 20%, such as about 12%, or even as low as 5%, and the atomic concentration of carbon at the top surface is greater than about 20%, such as about 36%, Even as high as 40%. With a higher concentration of carbon at the top surface, the top surface of graded SiCO films has a higher dry etch selectivity to oxides/nitrides than the bottom surface, is more resistant to ashing and stripping, and is more resistant to steam annealing processes. It has higher resistance to other rough integration steps such as. This allows graded SiCO films to meet multiple device integration requirements. With a lower concentration of carbon at the bottom surface, the bottom surface of the graded SiCO film has a lower dielectric constant, higher breakdown voltage, and lower leakage current than the top surface. This allows graded SiCO films to reduce parasitic capacitance, signal delay, and signal crosstalk, especially in high-speed devices.

In some embodiments, a surface with a lower carbon concentration may provide a lower dielectric constant, which may be less than about 5.0, or less than about 4.0, or less than about 3.5. The multilayer silicon carbide film can, for example, provide a dielectric constant of about 3.5 at the first surface and about 4.5 at the second surface. A graded silicon carbide film can, for example, provide a dielectric constant of about 3.5 at a first surface that gradually rises to a dielectric constant of about 4.5 at a second surface, where the graded silicon carbide film has a lower dielectric constant than a multilayer silicon carbide film. Provides a large buffer.

Figure 6 shows a graph illustrating compositional profiles of carbon concentration as a function of depth for graded and ungraded silicon carbide films. In ungraded SiCO films, the carbon concentration is generally constant throughout the thickness of the ungraded SiCO film. In graded SiCO films, the carbon concentration decreases across the thickness of the graded SiCO film from the exposed surface (e.g., top surface) to the unexposed surface (e.g., bottom surface). tilted downward to indicate As shown in Figure 5, as oxygen flow decreases over time, the carbon concentration may decrease from the exposed surface through the thickness of the film as shown in Figure 6. Alternatively, if the organosilicon precursor flow is reduced over time or the organosilicon precursor is changed to a lower carbon concentration, the carbon concentration can be reduced from the exposed surface through the thickness of the film as shown in Figure 6. .

Not only can graded silicon carbide films be deposited with varying carbon concentrations across the thickness of the graded silicon carbide films, but graded silicon carbide films can also be deposited with excellent conformality in high aspect ratio features. In some embodiments, graded silicon carbide films may be deposited in features having a depth-to-width aspect ratio greater than 2:1, greater than 5:1, or greater than 10:1. Even in these high aspect ratio features, the graded silicon carbide film can have a step coverage of at least 80%, at least 85%, or at least 90%. This step coverage can be useful in a variety of IC applications, such as sidewall spacer applications. Figure 7 illustrates a scanning transmission electron microscopy (STEM) image of an exemplary (graded or ungraded) SiCO film deposited within a feature of a substrate. Both graded and ungraded SiCO films maintain excellent conformality along the sidewalls of the features. To measure the elemental content in the features, an electron energy loss spectroscopy (EELS) operation is performed laterally.

FIG. 8A illustrates a line scan graph of the STEM image of FIG. 7 showing the composition profile of an ungraded SiCO film. In Figure 8A, the composition profile of the ungraded SiCO film can be seen at depths from about 70 nm to about 90 nm, and at depths from about 140 nm to about 160 nm. The relative concentrations of carbon and oxygen are generally constant in the ungraded SiCO film.

FIG. 8B illustrates a line scan graph of the STEM image of FIG. 7 showing the composition profile of a graded SiCO film. In FIG. 8B, the composition profile of the graded SiCO film can be seen at depths from about 70 nm to about 90 nm, and at depths from about 145 nm to about 165 nm. The relative concentrations of carbon and oxygen are more inclined in the graded SiCO film. Specifically, the relative concentration of carbon decreases from the outer surface to the inner surface and the relative concentration of oxygen increases from the outer surface to the inner surface. Therefore, as the number of Si-O bonds increases, the number of Si-C bonds decreases.

Device

One aspect of the disclosure is an apparatus configured to accomplish the methods described herein. A suitable apparatus includes hardware for accomplishing the process operations and a system controller with instructions for controlling the process operations in accordance with the present disclosure. In some embodiments, an apparatus for performing the above-described process operations may include a remote plasma source. Remote plasma sources provide milder reaction conditions compared to direct plasma. An example of a suitable remote plasma device is described in U.S. Patent Application Serial No. 14/062,648, filed October 24, 2013, the entire contents of which are incorporated herein by reference for all purposes.

3 shows a schematic diagram of a remote plasma device according to certain embodiments. Device 300 includes a reaction chamber 310 having a showerhead assembly 320 . Inside reaction chamber 310, substrate 330 is placed on a stage or pedestal 335. In some embodiments, pedestal 335 may fit with a heating/cooling element. A controller 340 may be coupled to components of device 300 to control the operation of device 300. For example, controller 340 may include instructions for controlling process conditions for operations of device 300, such as temperature process conditions and/or pressure process conditions. In some embodiments, controller 340 may include instructions for controlling flow rates of precursor gas, co-reactant gas, source gas, and carrier gas. Controller 340 may include instructions to change the flow rate of the co-reactant gas over time. Additionally or alternatively, controller 340 may include instructions to change the flow rate of the precursor gas over time.

During operation, gases or gas mixtures are introduced into the reaction chamber 310 through one or more gas inlets coupled to the reaction chamber 310. In some embodiments, two or more gas inlets are coupled to reaction chamber 310. A first gas inlet 355 can be coupled to the reaction chamber 310 and can be connected to a vessel 350, and a second gas inlet 365 can be coupled to the reaction chamber 310 and a remote plasma source. It can be connected to (360). In embodiments that include remote plasma configurations, delivery lines for precursors and radical species generated in the remote plasma source are separate. Accordingly, the precursors and radical species do not substantially interact before reaching the substrate 330.

One or more radical species may be generated at the remote plasma source 360 and may be configured to enter the reaction chamber 310 through the second gas inlet 365. Any type of plasma source may be used in remote plasma source 360 to generate radical species. This includes, but is not limited to, capacitively coupled plasmas, inductively coupled plasmas, microwave plasmas, DC plasmas, and laser-generated plasmas. An example of a capacitively coupled plasma may be a radio frequency (RF) plasma. The high-frequency plasma can be configured to operate above 13.56 MHz. An example of such a remote plasma source 360 may be GAMMA® manufactured by Lam Research Corporation of Fremont, California. Another example of such an RF remote plasma source 360 may be the Astron® manufactured by MKS Instruments of Wilmington, Massachusetts, which can operate at 440 kHz and can be used in larger devices for processing more than one substrate simultaneously. It may be provided as a bolted subunit. In some embodiments, microwave plasma may also be used as a remote plasma source 360, such as Astex® manufactured by MKS Instruments. The microwave plasma can be configured to operate at a frequency of 2.45 GHz. The gas provided to the remote plasma source may include hydrogen, nitrogen, oxygen, and other gases as mentioned elsewhere herein. In certain embodiments, hydrogen is provided in a carrier gas such as helium. As an example, hydrogen gas may be provided in a helium carrier at a concentration of hydrogen of about 1 to 10%.

Precursors may be provided in vessel 350 and supplied to showerhead 320 through first gas inlet 355. Showerhead 320 disperses precursors into reaction chamber 310 toward substrate 330 . Substrate 330 may be positioned beneath showerhead 320. It will be appreciated that the showerhead 320 may have any suitable shape and may have any number and arrangement of ports for dispersing gases to the substrate 330. Precursors may be supplied at a controlled flow rate to the showerhead 320 and ultimately to the substrate 330.

One or more radical species formed at the remote plasma source 360 may be transported in the gas phase toward the substrate 330. One or more radical species may flow into reaction chamber 310 through second gas inlet 365. It is understood that the second gas inlet 365 need not be perpendicular to the surface of the substrate 330 as illustrated in FIG. 3 . In certain embodiments, second gas inlet 365 may be directly above substrate 330 or at other locations. The distance between the remote plasma source 360 and the reaction chamber 310 is such that ionized species generated in the remote plasma source 360 are substantially neutralized, but at least some radical species in substantially low energy states are kept adjacent to the substrate 330. It can be configured to provide benign reaction conditions so that it remains in the environment. These low energy state radical species do not recombine to form stable compounds. The distance between the remote plasma source 360 and the reaction chamber 310 depends on the aggressiveness of the plasma (e.g., determined in part by the source RF power level), the density of gases in the plasma (e.g., high concentrations of hydrogen), A significant fraction of the atoms, if any, may recombine to form H ₂ before reaching reaction chamber 310), and other factors. In some embodiments, the distance between remote plasma source 360 and reaction chamber 310 may be about 1 cm to 30 cm, such as about 5 cm or about 15 cm.

In some embodiments, a co-reactant other than the primary silicon-containing precursor or hydrogen radical is introduced during the deposition reaction. In some implementations, the device is configured to introduce a co-reactant through the second gas inlet 365, where the co-reactant is at least partially converted to plasma. In some implementations, the device is configured to introduce the co-reactant through the showerhead 320 through the first gas inlet 355. Examples of co-reactants include oxygen, nitrogen, ammonia, carbon dioxide, carbon monoxide, etc. The flow rate of the co-reactants can be varied over time to create a compositional gradient in the graded membrane.

Controller 340 may include instructions to control process conditions for operation of device 300. Controller 340 will typically include one or more memory devices and one or more processors. The processor may include a CPU or computer, analog input/output connections and/or digital input/output connections, stepper motor controller boards, etc. Instructions for implementing appropriate control operations are executed on the processor. These instructions may be stored on memory devices associated with controller 340 or provided over a network.

In certain embodiments, controller 340 controls all or most activities of semiconductor processing device 300 described herein. For example, controller 340 may control all or most activities of semiconductor processing device 300 associated with depositing graded silicon carbide films or optionally other operations of a manufacturing flow including graded silicon carbide films. You can also control them. Controller 340 may execute system control software that includes sets of instructions for controlling timing, gas composition, gas flow rates, chamber pressure, chamber temperature, RF power levels, substrate position, and/or other parameters. . Other computer programs, scripts, or routines stored on memory devices associated with controller 340 may be employed in some embodiments. Parameters such as RF power levels, gas flow rate to the remote plasma region, and plasma ignition timing are adjusted by controller 340 to provide relatively benign reaction conditions in the environment adjacent to substrate 330. and can be maintained. Additionally, adjusting the substrate position may further reduce the presence of high-energy radical species in the environment adjacent to the substrate 330. In a multi-station reactor, controller 340 may include different or identical instructions for different device stations, allowing the device stations to operate independently or synchronously.

In some embodiments, the controller 340 may operate to flow a silicon-containing precursor into the reaction chamber 310 through the first gas inlet 355, converting one or more radical species of the source gas in a substantially low energy state into a remote plasma. providing from a source 360, flowing co-reactant gas into reaction chamber 310 through second gas inlet 365, and varying the flow rate of the co-reactant gas over time. , and flowing one or more radical species through the second gas inlet 365 into the reaction chamber 310 to react with the silicon-containing precursor to form a graded silicon carbide film on the substrate 330. It may also include instructions for execution. In some implementations, controller 340 may include instructions to change the flow rate of the silicon-containing precursor over time.

In some embodiments, the device may include a user interface associated with controller 340. The user interface may include a display screen, graphical software displays of device and/or process conditions, and user input devices such as pointing devices, keyboards, touch screens, microphones, etc.

Computer program code for controlling the operations may be written in any conventional computer-readable programming language: for example, assembly language, C, C++, Pascal, Fortran, or others. Compiled object code or script is executed by the processor to perform tasks identified within the program.

Signals for monitoring the process may be provided by analog input connections and/or digital input connections of the system controller. Signals for controlling the process are output to analog output connections and digital output connections of the process system.

Generally, the methods described herein utilize semiconductor processing equipment, such as a processing tool or tools, a chamber or chambers, a platform or platforms for processing, and/or specific processing components (wafer pedestals, gas flow systems, etc.). It can be performed on systems including: These systems may be integrated with electronics to control the operation of semiconductor wafers or substrates before, during, and after processing. Generally, electronic devices are referred to as “controllers” that may control a system or various components or sub-parts of systems. The controller controls delivery of processing gases, temperature settings (e.g., heating and/or cooling), pressure settings, vacuum settings, and power settings, depending on the processing requirements and/or type of system. , radio frequency (RF) generator settings, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, position and motion settings, tools and other transfer tools and/or It may also be programmed to control any of the processes disclosed herein, including wafer transfers into and out of loadlocks connected or interfaced with a particular system.

Generally speaking, a controller includes various integrated circuits, logic, memory, and/or components that receive instructions, issue instructions, control operations, enable cleaning operations, enable endpoint measurements, etc. It may also be defined as an electronic device with software. Integrated circuits are chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and/or one that executes program instructions (e.g., software). It may also include one or more microprocessors or microcontrollers. Program instructions may be instructions delivered to the controller or to the system in the form of various individual settings (or program files) that specify operating parameters for executing a particular process on or for a semiconductor wafer. In some embodiments, operating parameters are determined by a process engineer to accomplish one or more processing steps during fabrication of dies of one or more layers, materials (e.g., silicon carbide), surfaces, circuits, and/or wafers. It may be part of a prescribed recipe.

The controller may, in some implementations, be coupled to or part of a computer that may be integrated into the system, coupled to the system, otherwise networked to the system, or a combination thereof. For example, the controller may be all or part of a fab host computer system or within the “cloud,” which may enable remote access to wafer processing. The computer monitors the current progress of manufacturing operations, examines the history of past manufacturing operations, examines trends or performance metrics from multiple manufacturing operations, changes parameters of current processing, and performs processing steps that follow the current processing. You can also enable remote access to the system to configure, or start new processes. In some examples, a remote computer (eg, a server) may provide process recipes to the system over a network, which may include a local network or the Internet. The remote computer may include a user interface that enables entry or programming of parameters and/or settings to be subsequently transferred to the system from the remote computer. In some examples, the controller receives instructions in the form of data that specify parameters for each of the process steps to be performed during one or more operations. It should be understood that these parameters may be specific to the type of tool the controller is configured to control or interface with and the type of process to be performed. Accordingly, as discussed above, a controller may be distributed, for example by comprising one or more individual controllers that are networked together and cooperate together for a common purpose, for example the processes and controls described herein. An example of a distributed controller for this purpose is one or more integrated circuits on a chamber that communicate with one or more remotely located integrated circuits (e.g., at a platform level or as part of a remote computer) that combine to control processes on the chamber. It could be circuits.

In addition to the silicon carbide deposition described herein, exemplary systems include plasma etch chambers or modules, deposition chambers or modules, spin-rinse chambers or modules, metal plating chambers or modules, clean chambers or modules, and bevel edge etch chambers or modules. , physical vapor deposition (PVD) chamber or module, chemical vapor deposition (CVD) chamber or module, atomic layer deposition (ALD) chamber or module, atomic layer etch (ALE) chamber or module, ion implantation chamber or module, track ) chamber or module, and any other semiconductor processing systems that may be used or associated in the fabrication and/or fabrication of semiconductor wafers.

As described above, depending on the process step or steps to be performed by the tool, the controller may be used in material transfer to move containers of wafers to and from tool locations and/or load ports within the semiconductor fabrication plant. It may communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout the factory, a main computer, another controller or tools. .

The apparatus/process described above herein may be used in conjunction with lithographic patterning tools or processes for, for example, the fabrication or fabrication of semiconductor devices, displays, LEDs, photovoltaic panels, etc. Typically, although not necessarily, these tools/processes will be used or run together in a typical manufacturing facility. Lithographic patterning of a film typically involves the following operations, each of which is enabled using a number of possible tools: (1) a layer of photoresist on a workpiece, i.e., a substrate, using a spin-on or spray-on tool; The action of applying; (2) curing the photoresist using a hot plate or furnace or UV curing tool; (3) exposing the photoresist to visible or UV light or x-ray light using a tool such as a wafer stepper; (4) developing the resist for patterning using a tool such as a wet bench to selectively remove the resist; (5) transferring the resist pattern to the underlying film or workpiece using a dry or plasma-assisted etching tool; and (6) removing the resist using a tool such as an RF or microwave plasma resist stripper.

applications

The present disclosure may be further understood with reference to the following applications for high quality silicon carbide films, including graded silicon carbide films, which applications are intended to serve purely as examples. The present disclosure is not limited in scope by the specified applications, which are merely examples of aspects of the disclosure.

In some embodiments, a silicon carbide film may be deposited over the exposed copper. When depositing a silicon carbide film, reaction conditions adjacent to the substrate may be free of oxidizing agents such as O ₂ , O ₃ , and CO ₂ , including their radicals. Accordingly, a silicon carbide film may be deposited directly over the exposed copper without oxidizing the copper (e.g., creating copper oxide). These films can act as etch stop layers and also serve as copper diffusion barriers. The presence of a silicon carbide film can provide a sufficiently low dielectric constant along with excellent leakage properties to act as a diffusion barrier. Silicon carbide films can be prepared by themselves or as a bilayer stack (e.g., a silicon carbide/SiNC bilayer deposited on exposed copper), or as a graded film (e.g., a graded SiCO film) or a multilayer stack (e.g. For example, a multilayer SiCO film) may be an etch stop and/or diffusion barrier. In some embodiments, a silicon carbide film can be disposed between adjacent metallization layers, which are typically produced by a damascene process. The silicon carbide film can be resistant to etching and can be sufficiently dense to minimize diffusion of copper ions into adjacent areas of the dielectric material. In some embodiments, the precursor employed into the silicon carbide film may be non-cyclic. Non-cyclic precursors may include PMDSO or TMDSO. Non-cyclic precursors can provide sufficiently high densities to act as confinement or diffusion barriers. In some embodiments, nitrogen may be incorporated into the film by employing nitrogen-containing precursors or plasma activated nitrogen-containing radicals, such as elemental nitrogen radicals or amine radicals.

In some embodiments, the silicon carbide film may be deposited as vertical structures adjacent to the metal structure or semiconductor structure. Deposition of silicon carbide provides excellent step coverage along the sidewalls of a metallic or semiconductor structure to create vertical structures. In certain embodiments, vertical structures may be referred to as spacers or liners. 1B illustrates a cross-section of silicon carbide liners deposited on the sidewalls of the gate electrode structure of a transistor. As illustrated in FIG. 1B, the transistor may be a CMOS transistor with a silicon substrate 110 having a source 112 and a drain 113. A gate dielectric 114 can be deposited over the silicon substrate 110 and a gate electrode can be deposited over the gate dielectric 115 to form a transistor. Silicon carbide liners 111 may be deposited on the sidewalls of the gate electrode 115 and gate dielectric 114. In another example, Figure 1C illustrates a cross-section of silicon carbide deposited on the sidewalls of the exposed copper lines of an air gap type metallization layer. Air gaps 120 may be introduced into the IC layer between copper lines 122 and may reduce the effective k-value of the layer. Silicon carbide liners 121 can be deposited on the sidewalls of the copper lines 122 and a non-conformal dielectric layer 123 is formed on the air gaps 120, liners 121, and copper lines 122. ) can be deposited on. Examples of such air gap type metallization layers can be described in US Patent Publication No. 2004/0232552 to Fei Wang et al., incorporated herein by reference in its entirety for all purposes.

In some embodiments, a silicon carbide film may be deposited on the sidewalls of the patterned porous dielectric materials. ULK dielectric materials can be composed of porous structures. Pores in these materials can provide an area for ingress of metal during the deposition of subsequent layers, including the deposition of metal-containing diffusion barriers, such as tantalum (Ta). If too much metal migrates into the dielectric material, it may provide a short circuit between adjacent copper metallization lines. Figure 1D illustrates a cross section of silicon carbide as a pore sealer for porous dielectric materials. Porous dielectric layer 132 may have a plurality of trenches or vias cut into porous dielectric layer 132 to form pores 130 . Silicon carbide 131 may be deposited along the pores 130 to effectively seal the pores 130. Sealing the pores 130 using silicon carbide 131 can prevent damage to the porous dielectric layer 132 that might otherwise be caused by other sealing techniques using plasma. Silicon carbide 131 can be sufficiently dense as a pore sealant and may include non-cyclic silicon-containing precursors such as PMDSO and TMDSO. In some embodiments, the etched dielectric material, such as porous dielectric layer 132, may first be treated by a "k-recovery" process, exposing porous dielectric layer 132 to UV radiation and a reducing agent. This recovery process is further described in commonly owned U.S. Patent Publication No. 2011/0111533 to Varadarajan et al., which is hereby incorporated by reference in its entirety for all purposes. In another "recovery" process, a porous dielectric layer ( 132) can be exposed to UV radiation and chemical silylating agents.This recovery process is further described in US Patent Publication No. 2011/0117678, co-owned by Varadarajan et al., and is disclosed in its entirety for all purposes. Incorporated herein by reference. After exposing the pores 130 to a reparative treatment, which renders the surface more hydrophilic and provides a monolayer of material, the conformally deposited silicon carbide A layer of 131 may be deposited to effectively seal the pores of the porous dielectric layer 132.

In some embodiments, the silicon carbide film may be deposited as the ULK dielectric material itself. ULK dielectrics have previously been defined as materials with a dielectric constant lower than 2.5. In these configurations, the ULK dielectric material of silicon carbide may be a porous dielectric layer. Pores of the dielectric material can be introduced using cyclic or caged precursor molecules, including cyclic siloxanes and silsequinoxanes. In one example, the porosity of the ULK dielectric layer of silicon carbide may be about 20% to 50%. Additionally, the ULK dielectric layer may have an average pore size of less than about 100 Å, such as about 5 Å to 20 Å. For example, a cyclosiloxane ring may have a radius of approximately 6.7 Å. Increasing the number and size of pores can lower the dielectric constant, but the mechanical integrity of the dielectric layer can be compromised if the dielectric layer is highly porous.

Although the foregoing has been described in some detail for purposes of clarity and understanding, it will be apparent that certain changes and modifications may be made within the scope of the appended claims. It should be noted that there are many alternative ways of implementing the described processes, systems and devices. Accordingly, the described embodiments should be regarded as illustrative and not limiting.

Claims (19)

A method for depositing a graded silicon carbide film, comprising:
providing a substrate to a reaction chamber;
flowing an organosilicon precursor onto the substrate;
flowing a co-reactant gas toward the reaction chamber;
providing a source gas to a plasma source remote from the reaction chamber;
generating, from the source gas, one or more radicals of the source gas in the plasma source;
Introducing the one or more radicals of the source gas onto the substrate, wherein the co-reactant gas and the one or more radicals of the source gas react with the organosilicon precursor to deposit a silicon carbide film. introducing the one or more radicals of the source gas into the phase; and
The co-reactant gas and the one or more radicals of the source gas react with the organosilicon precursor over time to form a graded silicon carbide film from the silicon carbide film. Changing the flow rate of the reactant gas, wherein the graded silicon carbide film is moved from a first surface of the graded silicon carbide film to a second surface opposite the first surface of the graded silicon carbide film. a co-reactant gas having a compositional gradient to the surface, wherein varying the flow rate of the co-reactant gas over time tunes the carbon content of the graded silicon carbide film. A method of depositing a graded silicon carbide film comprising varying the flow rate of . According to claim 1,
Wherein flowing the co-reactant gas toward the reaction chamber includes flowing the co-reactant gas through the plasma source. According to claim 2,
generating, from the co-reactant gas, one or more radicals of the co-reactant gas of the plasma source; and
A method of depositing a graded silicon carbide film, further comprising introducing the one or more radicals of the co-reactant gas onto the substrate. According to claim 1,
Wherein flowing the co-reactant gas toward the reaction chamber comprises flowing the co-reactant gas in the same flow path as the organosilicon precursor. According to claim 1,
The co-reactant gases include carbon dioxide (CO ₂ ), carbon monoxide (CO), water (H ₂ O), methanol (CH ₃ OH), oxygen (O ₂ ), ozone (O ₃ ), nitrogen (N ₂ ), Nitrous oxide (N ₂ O), ammonia (NH ₃ ), diazene (N ₂ H ₂ ), methane (CH ₄ ), ethane (C ₂ H ₆ ), acetylene (C ₂ H ₂ ), ethylene ( A method of depositing a graded silicon carbide film comprising C ₂ H ₄ ), diborane (B ₂ H ₆ ), or combinations thereof. According to claim 5,
A method of depositing a graded silicon carbide film, wherein the co-reactant gas is oxygen gas. The method according to any one of claims 1 to 6,
A method of depositing a graded silicon carbide film, wherein the graded silicon carbide film is a graded oxygen-doped silicon carbide (SiCO) film. The method according to any one of claims 1 to 6,
and wherein the compositional gradient of the graded silicon carbide film has an increasing concentration of carbon from the first surface to the second surface of the graded silicon carbide film. According to claim 8,
wherein the atomic concentration of carbon at the first surface of the graded silicon carbide film is less than 20% and the atomic concentration of carbon at the second surface of the graded silicon carbide film is greater than 20%. Method for depositing silicon carbide films. According to claim 8,
The second surface has higher etch selectivity to oxides/nitrides, higher resistance to ash and stripping, and steam annealing than the first surface of the graded silicon carbide film. ) A method of depositing graded silicon carbide films with higher resistance to According to claim 8,
wherein the second surface has a higher dielectric constant than the first surface of the graded silicon carbide film. The method according to any one of claims 1 to 6,
A method of depositing a graded silicon carbide film, wherein the graded silicon carbide film is formed without introducing a vacuum break. The method according to any one of claims 1 to 6,
Changing the flow rate of the co-reactant gas over time includes gradually changing the flow rate of the co-reactant gas across a thickness of the graded silicon carbide film. Method for depositing graded silicon carbide films. The method according to any one of claims 1 to 6,
wherein the one or more radicals of the source gas comprise hydrogen radicals. The method according to any one of claims 1 to 6,
The organosilicon precursor comprises: (i) one or more silicon-hydrogen bonds and/or silicon-silicon bonds, (ii) one or more silicon-carbon bonds, and (iii) one or more silicon-oxygen bonds. Method for depositing graded silicon carbide films. According to claim 15,
The organosilicon precursor is selected from the group consisting of: cyclic siloxanes, linear siloxanes, and alkoxy siloxanes. The method according to any one of claims 1 to 6,
wherein the substrate has a plurality of features, each of the features having a depth-to-width aspect ratio of greater than 5:1. The method according to any one of claims 1 to 6,
wherein changing the flow rate of the co-reactant gas over time occurs without changing the flow rate of the organosilicon precursor or the flow rate of the source gas. . The method according to any one of claims 1 to 6,
A method of depositing a graded silicon carbide film, further comprising varying the flow rate of the organosilicon precursor over time.